Article
Physics, Multidisciplinary
Maudud Ahmed, Shubharaj Mukherjee, Tukai Singha, Jay Sharma, P. M. G. Nambissan
Summary: Pure and zinc-doped cadmium oxide nanocrystallites were synthesized using a chemical precipitation method with varying doping concentrations. The sizes of the nanocrystallites decreased with increasing substitution due to the smaller ionic radii of Zn2+. Interfacial defects were formed at higher doping concentrations due to the different crystalline structures of ZnO and CdO. Characterization was done through X-ray diffraction patterns, transmission electron microscopy, and optical band gap measurements. The results showed well-defined peaks, substitution-induced disorder, and a decrease in band gap energies. The segregation of ZnO phase hindered the success of continued substitution.
Article
Materials Science, Multidisciplinary
Luca Chiari, Kenji Kojima, Yusuke Endo, Hiroki Teshigahara, Maik Butterling, Maciej Oskar Liedke, Eric Hirschmann, Ahmed G. Attallah, Andeas Wagner, Masanori Fujinami
Summary: The formation and evolution of hydrogen-induced defects in nickel were investigated using positron annihilation lifetime spectroscopy, revealing that hydrogen addition at room temperature can lead to the formation of a large number of atomic vacancies. These defects in nickel agglomerate into large vacancy clusters during room temperature aging, demonstrating the primary role of hydrogen in the formation and stabilization of vacancies.
Article
Chemistry, Multidisciplinary
Maudud Ahmed, Shubharaj Mukherjee, Tukai Singha, P. M. G. Nambissan
Summary: In this study, cadmium oxide nanocrystallites with sizes ranging from 16 nm to 30 nm were synthesized via a chemical precipitation method at different synthesis temperatures. X-ray diffraction analysis confirmed the absence of mixed or impurity phases. The samples exhibited quantum confinement effects, as demonstrated by the variation in band gap energies measured by optical absorption. The presence of defects, such as non-stoichiometric defects, was found to greatly influence the properties of the nanocrystallites, and their concentration was quantified using positron annihilation studies.
JOURNAL OF PHYSICS AND CHEMISTRY OF SOLIDS
(2023)
Article
Materials Science, Ceramics
Priyanka Nayak, Sushri Sangita Nanda, Santosh K. Gupta, K. Sudarshan, S. Dash
Summary: This study demonstrates the efficient utilization of phosphors in solid-state lighting and phosphor-converted light-emitting diodes through the synthesis of undoped and Li+ co-doped CaMoO4:Dy3+ nanoparticles. The characteristic emission lines from Dy3+ are achieved through energy transfer from the host to the dopant. The optical properties of the phosphors are improved by lithium co-doping, resulting in enhanced light output and excited state lifetimes. This work highlights the importance of lithium co-doping in enhancing the optical properties of phosphors.
JOURNAL OF THE AMERICAN CERAMIC SOCIETY
(2022)
Article
Chemistry, Multidisciplinary
Cheolmin Park, Seonghun Ahn, Jun-Hwe Cha, Woonggi Hong, Hyeok Jun Jin, Sang Yoon Yang, Yong-Hoon Cho, Sung-Yool Choi
Summary: Despite having a large exciton binding energy, two-dimensional transition metal dichalcogenides (TMDs) face limitations as light-emitting materials due to the transfer of neutral excitons to trions and the occurrence of exciton-exciton annihilation (EEA). This study presents an isolated neutral exciton system with high spectral weight, achieved through MoS2 clusters synthesized on a MoS2 trilayer. By decomposing trions and observing the relationship between trions and B excitons, this research offers valuable insights into the radiative recombination processes in 2D TMDs.
Article
Materials Science, Multidisciplinary
Jonatan Slotte, Simo Kilpelainen, Natalie Segercrantz, Kenichiro Mizohata, Jyrki Raisanen, Filip Tuomisto
Summary: The unique experimental setup at the Accelerator Laboratory of the University of Helsinki allows for in situ positron annihilation spectroscopy (PAS) analysis on ion irradiated samples, with temperature control. This system provides numerous possibilities for defect identification and annealing studies, but also presents challenges and limitations that need to be addressed.
PHYSICA STATUS SOLIDI A-APPLICATIONS AND MATERIALS SCIENCE
(2021)
Article
Materials Science, Multidisciplinary
Jakub Cizek, Tomas Vlasak, Oksana Melikhova
Summary: Lattice defects in refractory metal high-entropy alloy HfNbTaTiZr were investigated using positron lifetime spectroscopy and coincidence Doppler broadening spectroscopy. The results showed that annealing the alloy at 1000 degrees C resulted in the full recovery of defects and the formation of a single-phase random solid solution. Quenching the alloy from high temperature prevented the recovery of thermally equilibrium vacancies and maintained a high concentration of vacancies at ambient temperature. The study also revealed that vacancies in the alloy were preferentially coupled with Hf solutes.
PHYSICA STATUS SOLIDI A-APPLICATIONS AND MATERIALS SCIENCE
(2022)
Article
Chemistry, Applied
J. Mor, S. K. Sharma, P. Utpalla, J. Bahadur, J. Prakash, Ashwani Kumar, P. K. Pujari
Summary: Tunable porosity through hollow features at nanoscale in metal organic frameworks (MOFs) has enormous potential applications in catalysis, with hollow core/shell frameworks showing improved catalytic activity compared to pure ZIF-67 nanocrystals.
MICROPOROUS AND MESOPOROUS MATERIALS
(2022)
Article
Chemistry, Inorganic & Nuclear
Ramachandrapanicker Devi Chandra, Lalan Veena, Kunnel Gopalan Gopchandran
Summary: Cobalt (Co)-doped ZnO nanoparticles were synthesized at 100°C using a simple chemical technique, resulting in nanoparticles with high crystallinity and reduced defect density. Co-doping suppressed oxygen-vacancy-related defects at lower doping densities, but increased defect density at higher doping densities. Co-doping was found to significantly suppress defects in ZnO for electronic and optoelectronic applications, as demonstrated by XPS, PL, electrical conductivity, and Mott-Schottky analysis. Photodetectors fabricated with Co-doped ZnO nanoparticles showed faster response time due to the reduced defect density.
INORGANIC CHEMISTRY
(2023)
Article
Chemistry, Physical
Alice Hospodkova, Jakub Cizek, Frantisek Hajek, Tomas Hubacek, Jiri Pangrac, Filip Dominec, Karla Kuldova, Jan Batysta, Maciej O. Liedke, Eric Hirschmann, Maik Butterling, Andreas Wagner
Summary: A set of GaN layers prepared by metalorganic vapor phase epitaxy under different technological conditions were investigated using variable energy positron annihilation spectroscopy to find a link between technological conditions, GaN layer properties, and the concentration of gallium vacancies (V-Ga). Different correlations between technological parameters and V-Ga concentration were observed for layers grown from different gallium precursors.
Article
Nanoscience & Nanotechnology
Z. H. Li, T. T. Sasaki, A. Uedono, K. Hono
Summary: This study investigates the role of Zn in the rapid age-hardening process of magnesium alloys. The results show that the addition of Zn facilitates the formation of Ca-Zn co-clusters, which contributes to the rapid age-hardening.
SCRIPTA MATERIALIA
(2022)
Article
Physics, Applied
Jani Jesenovec, Marc H. Weber, Christopher Pansegrau, Matthew D. McCluskey, Kelvin G. Lynn, John S. McCloy
Summary: This study explores the formation and character of gallium vacancies (V-Ga) and their complexes in near surface and bulk regions of single crystal beta-Ga2O3. The results suggest that defect changes from annealing in oxygen are depth dependent, and the configuration of V-Ga may differ near the oxygen-exposed surface of the sample and in the bulk.
JOURNAL OF APPLIED PHYSICS
(2021)
Article
Engineering, Electrical & Electronic
Kacper Sierakowski, Rafal Jakiela, Piotr Jaroszynski, Michal Fijalkowski, Tomasz Sochacki, Malgorzata Iwinska, Marcin Turek, Akira Uedono, Michael A. Reshchikov, Michal Bockowski
Summary: This work presents the diffusion mechanism of zinc in gallium nitride, showing a strong dependence of zinc diffusion on the crystallographic direction of gallium nitride crystal growth.
MATERIALS SCIENCE IN SEMICONDUCTOR PROCESSING
(2023)
Article
Engineering, Electrical & Electronic
Mitesh Chakraborty, Dhritiman Banerjee, Sujeet Singh, Joydip Dutta
Summary: The zinc oxide (ZnO) phosphors co-doped with Gd3+/Yb3+ were synthesized using the solid-state reaction method. The compound ZGYO {Zn(1 1.5x- 1.5y)GdxYbyO} was prepared for different molar concentrations of Yb (y) = 0.00, 0.01, 0.03, 0.05 and Gd (x) fixed at 0.01. XRD analysis confirmed the hexagonal phase of the ZnO wurtzite structure, while EDX and XPS spectra confirmed the successful incorporation of Gd3+ and Yb3+ in the ZnO lattice.
MATERIALS SCIENCE IN SEMICONDUCTOR PROCESSING
(2023)
Article
Chemistry, Physical
Agata Kowalska, Konrad Czerski, Pawel Horodek, Krzysztof Siemek, Mateusz Kaczmarski, Natalia Targosz-Sleczka, Mathieu Valat, Rakesh Dubey, Krzysztof Pyszniak, Marcin Turek, Andrzej Drozdziel, Justyna Slowik, Jolanta Baranowska
Summary: Low-energy nuclear reactions are strongly influenced by the crystal structure and defects of deuterated samples. In this study, zirconium samples were exposed to deuteron beams and investigated using X-ray diffraction and positron annihilation spectroscopy. The observed enhancement of the electron-screening effect at very low energies can be explained by the formation of vacancies during deuteron irradiation.
Article
Physics, Applied
Violet M. Poole, Jesse Huso, Matthew D. McCluskey
JOURNAL OF APPLIED PHYSICS
(2018)
Article
Engineering, Electrical & Electronic
Dinesh Thapa, Jesse Huso, Jeffrey Lapp, Negar Rajabi, John L. Morrison, Matthew D. McCluskey, Leah Bergman
JOURNAL OF MATERIALS SCIENCE-MATERIALS IN ELECTRONICS
(2018)
Article
Physics, Applied
Jesse Huso, Leah Bergman, Matthew D. McCluskey
JOURNAL OF APPLIED PHYSICS
(2019)
Article
Optics
Yinchuan Yu, Xianjun Ye, Matthew D. McCluskey
Article
Physics, Applied
Matthew D. McCluskey
JOURNAL OF APPLIED PHYSICS
(2020)
Editorial Material
Physics, Applied
Matthew D. McCluskey, Anderson Janotti
JOURNAL OF APPLIED PHYSICS
(2020)
Article
Nanoscience & Nanotechnology
Jeffrey Lapp, Dinesh Thapa, Jesse Huso, Amrah Canul, M. Grant Norton, Matthew D. McCluskey, Leah Bergman
Article
Instruments & Instrumentation
Yinchuan Yu, Matthew D. McCluskey
Summary: This paper discusses a method for identifying substances from their photoluminescence spectra using machine learning, with a high accuracy rate of over 90% and successfully identifying a mixed Ga2O3/ZnO sample.
APPLIED SPECTROSCOPY
(2022)
Article
Materials Science, Coatings & Films
Syeed E. Ahmed, Violet M. Poole, John Igo, Yi Gu, Matthew D. McCluskey
Summary: This paper investigates the laser-induced phase transitions of titanium dioxide thin films. Raman mapping reveals the formation of crystalline microstructures due to laser treatment, and the phase of crystalline regions depends on ambient conditions (vacuum versus air).
JOURNAL OF VACUUM SCIENCE & TECHNOLOGY A
(2021)
Article
Physics, Applied
Christopher Pansegrau, Matthew D. McCluskey
Summary: Annealed bulk crystals of barium titanate exhibit persistent photoconductivity at room temperature, which is characterized by the appearance of a broad infrared absorption peak and a reduction in electrical resistance. The mechanisms for PPC in barium titanate are similar to that of strontium titanate.
JOURNAL OF APPLIED PHYSICS
(2022)
Article
Engineering, Electrical & Electronic
Syeed E. Ahmed, Violet M. Poole, Jani Jesenovec, Benjamin L. Dutton, John S. McCloy, Matthew D. McCluskey
Summary: Annealing Ba1-xCaxTiO3 (BCTO) under a flowing humid 2% hydrogen-argon gas mixture results in room-temperature persistent photoconductivity (PPC). This is attributed to the presence of substitutional hydrogen impurities that can be photoexcited. The threshold photon energy for PPC in BCTO is lower than that of BaTiO3 and SrTiO3, and the effect is reversible upon annealing in air.
JOURNAL OF ELECTRONIC MATERIALS
(2023)
Article
Engineering, Electrical & Electronic
Hyun-Soo Lee, Mohammad Wahidur Rahman, Darpan Verma, Violet M. Poole, Roberto C. Myers, Matthew D. McCluskey, Siddharth Rajan
Summary: In this study, a method to achieve selectively patterned Mg-doped GaN layers using hydrogen drive-in through PECVD SiNx films is demonstrated. The method selectively deactivates activated Mg-doped GaN layers through low-temperature annealing and is optically verified through spatially resolved photoluminescence measurements.
JOURNAL OF VACUUM SCIENCE & TECHNOLOGY B
(2022)
Article
Engineering, Electrical & Electronic
Jacob R. Ritter, Marilia J. Caldas, Tales J. da Silva, Arrigo Calzolari, Matthew D. McCluskey
ACS APPLIED ELECTRONIC MATERIALS
(2020)
Article
Engineering, Electrical & Electronic
Syeed E. Ahmed, Jesse Huso, Jacob R. Ritter, John Igo, Yi Gu, Matthew D. McCluskey
JOURNAL OF VACUUM SCIENCE & TECHNOLOGY B
(2020)
Proceedings Paper
Materials Science, Multidisciplinary
Jacob R. Ritter, Kelvin G. Lynn, Matthew D. McCluskey
OXIDE-BASED MATERIALS AND DEVICES X
(2019)
